Answer:
y = 1000·1.20^x
Step-by-step explanation:
The form of an exponential function is ...
y = a·b^x
where 'a' is the initial value (y-intercept), and 'b' is the common ratio (growth factor).
The growth factor is related to the growth rate by ...
growth factor = 1 + growth rate
For a growth rate of 20%, the growth factor is ...
growth factor = 1 +20% = 1.20
__
The problem statement tells you the initial value is $1000, so your exponential function is ...
y = 1000·1.20^x . . . . . x is the number of years after the current year; y is the watch value in dollars
